Linear and nonlinear rheological behavior of native and debranched wazy rice starch gels

The rheological behaviours of native (WX) and debranched (DB) waxy rice starch gels in the linear viscoelastic (LVE) regime and non-linear (NL) regime were investigated using small amplitude oscillatory shear (SAOS), and large amplitude oscillatory shear (LAOS), respectively. Our results show that WX starch gels exhibited a wider LVE region than DB starch gels, and a scaling of G′ with frequency given by G’∼ω0.26. The G' and G” scaled nearly linear with concentration and were nearly independent of temperature in the tested range. The Lissajous plots showed a gradual yielding of the gels, followed by softening behavior. These results indicated that the WX gel has the characteristics of a weak particle gel (of non-entangled polymers). In contrast, the DB starch produced gels with a more stiff and brittle behavior. The shear moduli had a very strong concentration dependence (∼C10.30) and temperature dependence. The DB starch gel showed more abrupt yielding and strong softening behavior in the Lissajous curves. Creep measurements showed a lower compliance for these gels, and significant creep ringing. These observations suggest the DB starch gels consist of clusters of stiff polymers

Acute oral toxicity of zein nanoparticles with encapsulated gamma oryzanol in Sprague Dawley rats

Gamma oryzanol (GO) is well known for its antioxidant activity and health-promoting benefits. The gamma oryzanol-loaded zein nanoparticles (GOZNs) were successfully prepared in our previous study. In the present work, the acute oral toxicity of GOZNs was evaluated based on OECD guideline 420. GOZNs were fabricated by the liquid-liquid dispersion and lyophilized. The samples displayed a mean diameter of 311.20±3.01 nm and high loading capacity of 311.22±7.97 to 322.69±5.67 mg-GO/g-powder after 42-day storage at -18oC. Healthy female Sprague Dawley rats (8 weeks of age) were used for the experiments. Five female rats were administered a single dose of 2,000 mg GO/kg body weight via the oral route. Observations of toxicity signs were recorded for the first 24 hours, and the changes in the general physical conditions were monitored for 14 days before the gross necropsy on day 15. The results show that Sprague Dawley rats exhibited normal growth, and neither mortality nor acute toxicity signs were observed throughout the study period. The findings revealed that GOZNs did not have acute toxicity and were safe when administered orally in Sprague Dawley rats for short periods with LD50 > 2,000 mg/kg

Screening, identification, and characterization of high potential bacteria for -cryptoxanthin production from natural sources

ꞵ-Cryptoxanthin is a carotenoid compound that presents several benefits, including provitamin A, prevention of bone loss, anti-obesity, antioxidant activities, anti-inflammatory, and anti-cancer activity. Bacteria are microorganisms of significant interest for ꞵ-cryptoxanthin production due to their short cultivation times and high yields. In this study, we aimed to screen ꞵ-cryptoxanthin producing-bacteria, which were isolated from three different sources, including surface marine water, soil, and flowers. The isolated bacterium strain from Tecoma stans (yellow elder), with a yellow pigment colony that can produce ꞵ-cryptoxanthin, zeaxanthin, and ꞵ-carotene, was identified by 16S rRNA as Pantoea anthophila FL1_IS5 strain. The carotenoids produced by this strain were identified and quantified by high performance liquid chromatography (HPLC) and high-resolution mass spectrometry (LC-HRMS/MS). Furthermore, the whole genome sequencing of P. anthophila FL1_IS5 was analyzed to confirm the carotenoids synthesis pathway and revealed the presence of the genes idi and CrtBIEXYZ. The optimized concentration of glucose and yeast extract to be added as carbon and nitrogen sources, in nutrient broth (NB) medium (10 g/L and 5 g/L, respectively), resulted in the highest cell biomass of 2.03 ± 0.08 g/L and ꞵ-cryptoxanthin production at 10.59 ± 0.14 mg/L. These results indicate high potential for ꞵ-cryptoxanthin production by the isolated bacterial strain

Optimization of Extrusion Process for Pentosanase-Supplemented Swine Feed: Evaluation of Physical Properties and Enzyme Stability

Extrusion of pentosanase supplemented swine feed to improve digestibility was optimized and the extrudates’ physical properties, and enzyme stability were investigated. The effects of feed moisture content, die end temperature, and screw speed on product responses, including expansion ratio, bulk density, and hardness were evaluated using the response surface methodology. Following conditions yielded the swine feed with physical properties comparable to the commercial products, feed moisture content at 18–21% (w/w), die end temperature of 95–120 °C, and screw speed at 100–150 rpm. Crude pentosanase was added to the ingredients at 0.5 g/kg and extruded with 2 levels of die end temperature at 95 and 110 °C. Residual activity of pentosanase in extruded swine feed indicated that an increase in die end temperature reduced the activity by 34–35%. Higher activity and stability of pentosanase were observed at pH 3.0 compared to pH 6.8. A significant decrease in the enzyme activity was observed during a 4 week storage period at room temperature. Optimal conditions for the extrusion of pentosanase-supplemented swine feed were obtained. However, the enzyme stabilization in extruded swine feed during the long storage requires further study

Effect of glucomannan and potassium sorbate on quality and shelf life of fresh-cut cantaloupe

The objective of this research was to study the effects of glucomannan, and potassium sorbate on the quality and shelf-life of fresh-cut cantaloupes, which were stored at 6±2°C for 9 days. The concentrations of glucomannan studied were 0.05, 0.10, 0.15 and 0.20% (w/v). Results indicated that the coating solution containing 0.5% (w/v) of calcium chloride and 0.05% (w/v) glucomannan could help maintain weight loss, hardness and firmness, of the samples. However, the increase of glucomannan concentration to 0.10, 0.15, and 0.20% (w/v) showed adverse effects to most quality aspects of the fresh-cut samples. The microbial load of the coated cantaloupe at all concentrations of glucomannan was still high and could extend the shelf life of the samples to 1 day or less. Subsequently, the optimal concentration of potassium sorbate was investigated at 0.05, 0.10, and 0.15% (w/v). Results indicated that the coating solution containing 0.5% (w/v) of calcium chloride and 0.05% (w/v) glucomannan could inhibit the microbial growth, especially bacteria at all concentrations of potassium sorbate studied. Additionally, the coating mixture with potassium sorbate at 0.15% (w/v) could preserve the fresh-cut cantaloupes for a maximum of 5 days with safer microbial loads for commercial use.This article is published as Morakot, N., Vatanyoopaisarn, S., Thumthanaruk, B., Wongsa, J., Puttanlek, C., Uttapap, D., Lamsal, B.P. and Rungsardthong, V., 2020. Effect of glucomannan and potassium sorbate on quality and shelf life of fresh-cut cantaloupe, Science, Engineering and Health Studies 14: 123-131

Preparation and characterization of gamma oryzanol loaded zein nanoparticles and its improved stability

Gamma oryzanol (GO), a bioactive ingredient found in rice bran oil, performs a variety of biological effects such as antioxidant activity, reduction of total cholesterol, anti-inflammation, and antidiabetes. However, GO is water-insoluble and normally degrades through oxidation. Thus a nano-encapsulation technique was investigated to improve its stability and quality. In this research, gamma oryzanol was successfully encapsulated into zein nanoparticles. The fabrication parameters including pH, zein concentration (0.3, 0.4, and 0.5% w/v), and % GO loading (30, 40, and 50% by weight) were investigated. Particle size, zeta potential, yield, encapsulation efficiency and the stability or GO retention during the storage were determined. The morphology of gamma oryzanol loaded zein nanoparticles (GOZNs) was observed by scanning electron micrographs and transmission electron microscope. The increase of zein concentration and % GO loading resulted to an increase of yield, encapsulation efficiency, and particle size. The particle size of the GOZNs ranged from 93.24–350.93, and 144.13–833.27, and 145.27–993.13 nm for each zein concentration with 3 loading levels, respectively. Nano-encapsulation exhibited higher % GO retention compared with nonencapsulated GO during 60 days storage both at 4°C and −18°C. In vitro study indicated the sustained release of GO in the simulated gastric fluid followed by simulated intestinal fluid. This finding indicated a high potential for the application of insoluble GO with improved stability by encapsulation with the hydrophobic zein protein